Cleanup: Rename `BKE_library_idmap` file to `BKE_main_idmap`

Part of T72604:
> Proposal: BKE_library and BKE_main API naming: prefixes conventions

1 files changed, 214 insertions, 0 deletions

diff --git a/source/blender/blenkernel/intern/main_idmap.c b/source/blender/blenkernel/intern/main_idmap.c
new file mode 100644
index 00000000000..a210961b212
--- /dev/null
+++ b/source/blender/blenkernel/intern/main_idmap.c
@@ -0,0 +1,214 @@
+/*
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ */
+
+#include <string.h>
+#include <stdlib.h>
+
+#include "MEM_guardedalloc.h"
+
+#include "BLI_utildefines.h"
+#include "BLI_ghash.h"
+#include "BLI_listbase.h"
+
+#include "DNA_ID.h"
+
+#include "BKE_idcode.h"
+#include "BKE_main.h"
+#include "BKE_main_idmap.h" /* own include */
+
+/** \file
+ * \ingroup bke
+ *
+ * Utility functions for faster ID lookups.
+ */
+
+/** \name BKE_main_idmap API
+ *
+ * Cache ID (name, library lookups).
+ * This doesn't account for adding/removing data-blocks,
+ * and should only be used when performing many lookups.
+ *
+ * \note GHash's are initialized on demand,
+ * since its likely some types will never have lookups run on them,
+ * so its a waste to create and never use.
+ * \{ */
+
+struct IDNameLib_Key {
+  /** ``ID.name + 2``: without the ID type prefix, since each id type gets it's own 'map' */
+  const char *name;
+  /** ``ID.lib``: */
+  const Library *lib;
+};
+
+struct IDNameLib_TypeMap {
+  GHash *map;
+  short id_type;
+  /* only for storage of keys in the ghash, avoid many single allocs */
+  struct IDNameLib_Key *keys;
+};
+
+/**
+ * Opaque structure, external API users only see this.
+ */
+struct IDNameLib_Map {
+  struct IDNameLib_TypeMap type_maps[MAX_LIBARRAY];
+  struct Main *bmain;
+  struct GSet *valid_id_pointers;
+};
+
+static struct IDNameLib_TypeMap *main_idmap_from_idcode(struct IDNameLib_Map *id_map,
+                                                        short id_type)
+{
+  for (int i = 0; i < MAX_LIBARRAY; i++) {
+    if (id_map->type_maps[i].id_type == id_type) {
+      return &id_map->type_maps[i];
+    }
+  }
+  return NULL;
+}
+
+/**
+ * Generate mapping from ID type/name to ID pointer for given \a bmain.
+ *
+ * \note When used during undo/redo, there is no guaranty that ID pointers from UI area
+ *       are not pointing to freed memory (when some IDs have been deleted). To avoid crashes
+ *       in those cases, one can provide the 'old' (aka current) Main database as reference.
+ *       #BKE_main_idmap_lookup_id will then check that given ID does exist in \a old_bmain
+ *       before trying to use it.
+ *
+ * \param create_valid_ids_set: If \a true, generate a reference to prevent freed memory accesses.
+ * \param old_bmain: If not NULL, its IDs will be added the valid references set.
+ */
+struct IDNameLib_Map *BKE_main_idmap_create(struct Main *bmain,
+                                            const bool create_valid_ids_set,
+                                            struct Main *old_bmain)
+{
+  struct IDNameLib_Map *id_map = MEM_mallocN(sizeof(*id_map), __func__);
+
+  int index = 0;
+  while (index < MAX_LIBARRAY) {
+    struct IDNameLib_TypeMap *type_map = &id_map->type_maps[index];
+    type_map->map = NULL;
+    type_map->id_type = BKE_idcode_iter_step(&index);
+    BLI_assert(type_map->id_type != 0);
+  }
+  BLI_assert(index == MAX_LIBARRAY);
+
+  id_map->bmain = bmain;
+
+  if (create_valid_ids_set) {
+    id_map->valid_id_pointers = BKE_main_gset_create(bmain, NULL);
+    if (old_bmain != NULL) {
+      id_map->valid_id_pointers = BKE_main_gset_create(old_bmain, id_map->valid_id_pointers);
+    }
+  }
+  else {
+    id_map->valid_id_pointers = NULL;
+  }
+
+  return id_map;
+}
+
+struct Main *BKE_main_idmap_main_get(struct IDNameLib_Map *id_map)
+{
+  return id_map->bmain;
+}
+
+static unsigned int idkey_hash(const void *ptr)
+{
+  const struct IDNameLib_Key *idkey = ptr;
+  unsigned int key = BLI_ghashutil_strhash(idkey->name);
+  if (idkey->lib) {
+    key ^= BLI_ghashutil_ptrhash(idkey->lib);
+  }
+  return key;
+}
+
+static bool idkey_cmp(const void *a, const void *b)
+{
+  const struct IDNameLib_Key *idkey_a = a;
+  const struct IDNameLib_Key *idkey_b = b;
+  return strcmp(idkey_a->name, idkey_b->name) || (idkey_a->lib != idkey_b->lib);
+}
+
+ID *BKE_main_idmap_lookup(struct IDNameLib_Map *id_map,
+                          short id_type,
+                          const char *name,
+                          const Library *lib)
+{
+  struct IDNameLib_TypeMap *type_map = main_idmap_from_idcode(id_map, id_type);
+
+  if (UNLIKELY(type_map == NULL)) {
+    return NULL;
+  }
+
+  /* lazy init */
+  if (type_map->map == NULL) {
+    ListBase *lb = which_libbase(id_map->bmain, id_type);
+    const int lb_len = BLI_listbase_count(lb);
+    if (lb_len == 0) {
+      return NULL;
+    }
+    type_map->map = BLI_ghash_new_ex(idkey_hash, idkey_cmp, __func__, lb_len);
+    type_map->keys = MEM_mallocN(sizeof(struct IDNameLib_Key) * lb_len, __func__);
+
+    GHash *map = type_map->map;
+    struct IDNameLib_Key *key = type_map->keys;
+
+    for (ID *id = lb->first; id; id = id->next, key++) {
+      key->name = id->name + 2;
+      key->lib = id->lib;
+      BLI_ghash_insert(map, key, id);
+    }
+  }
+
+  const struct IDNameLib_Key key_lookup = {name, lib};
+  return BLI_ghash_lookup(type_map->map, &key_lookup);
+}
+
+ID *BKE_main_idmap_lookup_id(struct IDNameLib_Map *id_map, const ID *id)
+{
+  /* When used during undo/redo, this function cannot assume that given id points to valid memory
+   * (i.e. has not been freed),
+   * so it has to check that it does exist in 'old' (aka current) Main database.
+   * Otherwise, we cannot provide new ID pointer that way (would crash accessing freed memory
+   * when trying to get ID name).
+   */
+  if (id_map->valid_id_pointers == NULL || BLI_gset_haskey(id_map->valid_id_pointers, id)) {
+    return BKE_main_idmap_lookup(id_map, GS(id->name), id->name + 2, id->lib);
+  }
+  return NULL;
+}
+
+void BKE_main_idmap_destroy(struct IDNameLib_Map *id_map)
+{
+  struct IDNameLib_TypeMap *type_map = id_map->type_maps;
+  for (int i = 0; i < MAX_LIBARRAY; i++, type_map++) {
+    if (type_map->map) {
+      BLI_ghash_free(type_map->map, NULL, NULL);
+      type_map->map = NULL;
+      MEM_freeN(type_map->keys);
+    }
+  }
+
+  if (id_map->valid_id_pointers != NULL) {
+    BLI_gset_free(id_map->valid_id_pointers, NULL);
+  }
+
+  MEM_freeN(id_map);
+}
+
+/** \} */